Profile Racing BMX IMPERIAL Sprocket is a used aluminum sprocket with 25 teeth and a 3/32" chainring. It is compatible with BMX bikes and has a 19/22mm spindle mounting type - the spacer/washer for a 19mm spindle is installed. This sprocket was on my BMX bike for a year or two, and it's been sitting around for a while. Teeth show wear - see photos for details.